Ion beam sample preparation apparatus and methods

Abstract

Disclosed are embodiments of an ion beam sample preparation apparatus and methods. The methods operate on a sample disposed in a vacuum chamber and include steps of directing an intensity-controllable, tilt-angle controllable ion beam at a sample holder coupled to a rotation stage. The methods further include illuminating and capturing one or more images of the sample, extracting useful features from one or more images and thereafter adjusting the sample preparation steps. Further methods are disclosed for capturing sequences of images, programmatically rotating images, and displaying sequences of images with similar rotation angles. Further methods include extracting useful features from sequences of images that may change with respect to time as ion beam preparation continues.

The invention claimed is: 
     
       1. An ion beam sample preparation method comprising the steps of:
 directing an ion beam having an intensity and having a first tilt angle toward a sample such that at least a portion of said sample is prepared by said ion beam inside a vacuum chamber; 
 illuminating at least a portion of said sample; 
 rotating said sample using a rotation stage having a rotation axis that substantially intersects a portion of said ion beam, said rotation stage being operable to rotate said sample with respect to said ion beam while said sample is prepared by said ion beam; 
 capturing a substantially focused image of at least a portion of said sample; 
 extracting in an instrument controller one or more features from said captured image, wherein the one or more features comprises at least one of a size of a portion of said captured image, a color in a portion of said captured image, a shape in a portion of said captured image, an intensity in a portion of said captured image, or a portion of an optical interference ring in a portion of said captured image; 
 determining, based on the one or more extracted features, whether a stopping condition has been detected; and 
 performing, via said instrument controller and in response to determining that the stopping condition has not been detected, at least one of: changing the first tilt angle of said ion beam to a second tilt angle, changing the intensity of said ion beam, or changing a rotation angle of said rotation stage. 
 
     
     
       2. The method of  claim 1 , wherein at least one of the extracted features comprises: a color in a portion of said captured image or a portion of an optical interference ring in a portion of said captured image. 
     
     
       3. The method of  claim 1 , wherein said capturing a substantially focused image of at least a portion of said sample, is preceded by rotating said rotation stage to a predetermined position. 
     
     
       4. The method of  claim 1 , wherein said capturing a substantially focused image of at least a portion of said sample, is preceded by waiting until a predetermined time. 
     
     
       5. The method of  claim 1 , further comprising:
 estimating in said instrument controller a future time for performing the at least one of: changing the first tilt angle of said ion beam to a second tilt angle; changing the intensity of said ion beam; or changing the rotation angle of said rotation stage. 
 
     
     
       6. The method of  claim 1 , wherein one or more of said features extracted from said captured image is representative of the stopping condition. 
     
     
       7. The method of  claim 1 , wherein the at least one extracted feature comprises a size of the portion of the captured image, or a shape in the portion of the captured image. 
     
     
       8. The method of  claim 1 , wherein the at least one extracted feature comprises an intensity in the portion of the captured image. 
     
     
       9. An ion beam sample preparation method comprising the steps of:
 directing an ion beam having an intensity and having a first tilt angle toward a sample such that at least a portion of said sample is prepared by said ion beam inside a vacuum chamber; 
 illuminating at least a portion of said sample; 
 rotating said sample using a rotation stage having a rotation axis that substantially intersects a portion of said ion beam, said rotation stage being operable to rotate said sample with respect to said ion beam while said sample is prepared by said ion beam; 
 capturing a sequence of more than one image of said sample in which each image of said sequence is substantially focused; 
 extracting in an instrument controller one or more features from said captured sequence of more than one image, wherein the one or more features comprises at least one of a change with respect to time of a size of a portion of said captured image, a change with respect to time of a color in a portion of said captured image, a change with respect to time of a shape in a portion of said captured image, a change with respect to time of an intensity in a portion of said captured image, or a change with respect to time of a portion of an optical interference ring in a portion of said captured image; and 
 performing, via said instrument controller and based on the one or more features from said captured sequence of more than one image, at least one of: changing the first tilt angle of said ion beam to a second tilt angle, changing the intensity of said ion beam, or changing the position of said rotation stage. 
 
     
     
       10. The method of  claim 9 , wherein at least one of the features extracted from said sequence of more than one image comprises: the change with respect to time of a size of a portion of said captured image, or the change with respect to time of an intensity in a portion of said captured image. 
     
     
       11. The method of  claim 9 , wherein each image of the sequence is captured with said rotation stage positioned at substantially a same rotation angle. 
     
     
       12. The method of  claim 11 , further comprising:
 displaying said sequence of more than one image in the same order as said sequence of more than one image was captured. 
 
     
     
       13. The method of  claim 9 , further comprising:
 processing the instrument controller one or more captured images wherein a rotation angle at which each of said one or more captured images is captured is different; and 
 producing one or more programmatically rotated images, wherein each of said one or more programmatically rotated images corresponds to said one or more captured images, and wherein each of said one or more programmatically rotated images appears to have been captured at substantially the same predetermined rotation angle. 
 
     
     
       14. The method of  claim 13 , further comprising:
 displaying said programmatically rotated images. 
 
     
     
       15. The method of  claim 13 , further comprising:
 extracting via the instrument controller one or more features from said programmatically rotated images; and 
 performing, via said instrument controller and based on the one or more features from said programmatically rotated images, at least one of: changing the first tilt angle of said ion beam to a second tilt angle, changing the intensity of said ion beam, or changing the position of said rotation stage. 
 
     
     
       16. The method of  claim 13 , further comprising:
 storing said one or more programmatically rotated images; 
 retrieving said one or more programmatically rotated images; and 
 displaying said one or more programmatically rotated images. 
 
     
     
       17. The method of  claim 9 , further comprising:
 determining, based on the one or more features, whether a stopping condition has been detected. 
 
     
     
       18. An ion beam sample preparation method comprising:
 directing an ion beam having an intensity and having a first tilt angle toward a sample such that at least a portion of said sample is prepared by said ion beam inside a vacuum chamber; 
 illuminating at least a portion of said sample; 
 rotating said sample using a rotation stage having a rotation axis that substantially intersects a portion of said ion beam, said rotation stage being operable to rotate said sample with respect to said ion beam while said sample is prepared by said ion beam; 
 capturing a substantially focused image of at least a portion of said sample; 
 capturing the rotation angle of said rotation stage at which said substantially focused image was captured; and 
 processing via an instrument controller said substantially focused image to produce a programmatically rotated image having an apparent rotation angle that is different from a rotation angle at which said substantially focused image was captured. 
 
     
     
       19. The method of  claim 18 , further comprising:
 displaying one or more of said programmatically rotated images. 
 
     
     
       20. The method of  claim 18 , further comprising the steps of:
 extracting via the instrument controller one or more features from said programmatically rotated image; and 
 responding in said instrument controller to the extraction of said one or more features from said programmatically rotated image by performing at least one of: 
 changing the tilt angle of said ion beam to a second tilt angle, changing the intensity of said ion beam, or changing the position of said rotation stage.